Remove prints and _str_ from the code
Removed length, area and volumne as they are calculated properties
copying lists of nodes and coordinates instead of their values. This is not the final solution for points
Implemented some suggested performance improvements
Type is no longer checked in add_xxx() as they only have to fulfill their interfaces
changed the way the points are added to be consisten with the rest of the code
Points are now stored by id instead of by reference
Points id are now uuid
This commit should solve the problem with non updated points after updating an elements, as they to be stored separately